


Underestimated

by Antimatics



Category: Sherlock (TV)
Genre: AU, Alternate Universe, Alternate Universe - High School, Animal Abuse, Animal Death, Badboy!Seb, Blood, Bullying, Canonical Character Death, Deductions, Gore, Gun Violence, Gunplay, High School AU, Implied/Referenced Drug Use, Jim is 16, John is 17, Knifeplay, Knives, M/M, Molly is 15, Molly is Seb's lil sister, Murder, Nerd!Jim, Painplay, Physical Abuse, Piercings, Sebastian is 18, Self-Harm, Sherlock is 17, Smoking, Suicidal Thoughts, Tattoos, Verbal Abuse, Violence, mormor
Language: English
Status: In-Progress
Published: 2016-01-18
Updated: 2016-01-29
Packaged: 2018-05-14 15:53:24
Rating: Mature
Warnings: Graphic Depictions Of Violence, Rape/Non-Con, Underage
Chapters: 4
Words: 4,104
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5749051
Author URL: https://archiveofourown.org/users/Antimatics/pseuds/Antimatics
Summary: <blockquote class="userstuff">
              <p>Sebastian Moran is the notorious 'bad boy' of the school, he comes school hungover and won't hesitate to start a fight with anyone who so much as looks at him the wrong way. James Moriarty is an invisible nerd who never gets in the way and never gets a bad grade. </p>
<p>Seb thinks nothing of the skinny little nerd in the year below him. Jim thinks everyone in his school is an imbecile.</p>
<p>A mysterious death in their small town changes everything.</p>
            </blockquote>





	1. Person of Interest

Idiots. The entire building was full of idiots. They were the mentally-impaired straws of hay and he was the sharp, glistening needle in their midst. It was hard to believe any of them could be classified as fellow homo-sapiens when they acted so similar to their ape ancestors. They screeched at one another, flung their limbs about, and performed their strange mating rituals right in the middle of the hallways. 

James Moriarty might as well have been an alien coming to Earth for the first time. An entire summer away from this prison had almost made him forget just how disgusting the remainder of the human population was. He clutched his books tighter to his chest, glaring at a boy who had the audacity to nearly crash into him. The boy took no notice and shoved his friend back into the lockers playfully, laughing stupidly.

It was a Monday. The first of many Mondays in his junior year of high school. He had finally been allowed to take advanced classes this year, though he expected that they would still fail to pose a challenge to him. Regardless, he needed the grades to keep up his 'harmless nerd' façade.

Jim walked into his first period class, calculus. An easy subject. He took a seat in the center of the room, a neutral position. The bell rang as he got out his materials, the same ones he used last year. He looked around at the rest of the class, nobody of interest unfortunately. All of these people could be read like a book.   
The popular girl to his left had been smoking weed before class and owned an orange tabby cat. Her boyfriend had hit her about a week ago (probably in a drunken fit) and had most likely promised it would never happen again. Jim snorted. He knew how those promises went.

The boy to his left had gone through a growth spurt over the summer and needed glasses but refused to wear them. He had subtle lines around his eyes from squinting at things too far away to see clearly. The scuffs on his shoes and the dirt under his torn nails spoke of a lot of time spent outside, maybe to get away from his family. 

Their teacher was an alcoholic and still lived with his mother. The girl in the front row had attempted suicide. The boy three seats away from her was bulimic. They all were simple. They held no interest to him. Not much did. It was like being dead. 

*

Class dragged on and on but eventually ended. Every class was like the last. French was too slow, in chemistry they went over the syllabus for the whole hour, English and history were the same. He’d already finished reading the psychology textbook last month. All in all, the day was a waste of time. 

After classes he walked home, a slight limp in his step from being tripped in the hallway on his way out. He changed his gait to aggravate the injury as much as possible, focusing on the pain with a vague sense of amusement. His other bruises had started hurting less and were no longer a source of amusement to him. He’d have to piss of his father again. Easy enough.

On the front step of his tiny house was small feathery lump. He picked it up, it was a sparrow. It seemed like its wing was broken. Its eyes looked up at him pitifully and it gave a small sound of pain at his touch. He smirked at it, placing it in the pocket of his jacket.

The house was dark, so either nobody was home or his mother was sulking in the dining room again. Same thing, really. He went to his tiny bedroom and threw his bag on the cot in the corner. He put the bird in an empty shoebox in the corner, checking on the snake he’d caught a few days ago. It was still in its crate, and hissed aggressively at him, rearing it head in warning. That was rude. He’d have to dispose of it later then.

Jim got up and stretched, he’d finished his homework in class already out of boredom. He sprawled on his back and stared at the water-stained ceiling, drifting in and out of sleep.

*

Sebastian Moran didn’t go to school that Monday, or for the rest of the week. He spent the days sleeping and the nights either at parties or watching shitty horror movies in his room. His sister had told him about her becoming captain of the science club (‘Nobody else wanted to do it but it was still an accomplishment’ she insisted). Molly had been practically bouncing off the walls in her excitement to be a high schooler all summer. Sebastian honestly had no idea why she was so excited.

After a week of nagging from his sister and disappointed looks from his mother he agreed to go to class next Monday. At least he never specified how long he’d stay.

*

The only interesting things that had happened to Jim that week had been the dissection of that snake (it had writhed and hissed so wonderfully when he pressed his knife into its belly), the eventual dehydration the bird had succumbed to, and his father leaving a bruise across his left side that had turned green and black (the skin was strangely hot and squishy feeling).

Everything else was mind-numbing. Boring. Even the collage of cuts and burns on his arms he’d created hadn’t staved of the boredom for more than a few moments. The weekends were even worse than the weekdays, he only had more time to fill. 

*

When Monday Number Two came around Jim was almost grateful for the drone of his teachers. Better than silence at least. His first two class were identical to last week’s classes, but chemistry was unexpectedly different.

There was a new kid in class. Well, not new but Jim had never had a class with him. The notorious Sebastian Moran, the boy with bruised knuckled that you could never bring home to mama. His pretty boy looks: windswept blonde hair and sky blue eyes. Girls stole glances at him throughout the entire class, blushing heavily and giggling if they were caught looking. Sebastian would send them smiles that, to Jim’s eyes, were like that of a shark spotting their next meal.

Jim had never spent that much time deducing Sebastian’s life. He had never had to spend much time on any of the other morons in this school. But now that the boy was in front of him, he found it hard to see everything.

He could see basic things, Sebastian’s family owned a large grey dog (the creature’s fur was on Sebastian’s sleeve), he smoked (nail beds), he hadn’t slept for at least twenty four hours (dark circles under the eyes), and the rumors were true, he fought a lot (bruised knuckles and healing split lip). But there was more he couldn’t see yet. Something interesting.

For the first time since he’d met Sherlock Holmes, James Moriarty knew he had to have this man. He had to have Sebastian Moran. He had to see all of his secrets and turn that confidence into submission. All he had to do was peel back his skin and rip out his insides until he knew every inch of Sebastian’s mind. Then, he’d put it all back in an order Jim could appreciate.


	2. What You Don't Know Might Kill You

**Summary for the Chapter:**

> Sebastian sees Jim. The real Jim.

A month passed. Jim knew more about Sebastian now, he knew his address, birthday, height, and weight. He could tell you exactly how much alcohol it took to get Sebastian drunk, and the names of everyone Sebastian had beaten up or had smiled at. 

Everything else had gone downhill. Jim’s mother had tried to kill herself (again) but hadn’t tied her noose correctly and had ended up with another neck injury. His father had blamed Jim for her failure, had beaten him into unconsciousness and hadn’t let him eat for a week. Jim had had to borrow his mother’s concealer again. His neighbors figured out where their cat was getting all the burns and cuts from and had taken to shutting her inside. People at school treated him worse than last year, and his need to hurt something was only getting worse.

All he could do was hurt himself, and any animals he came across on his walks home. He could no longer go anywhere without long sleeves on and if he was one for wear shorts then he would’ve had to quit them as well. 

The only thing of interest was Sebastian, and even then he wasn’t much. He wasn’t like Sherlock. Sebastian could never match his intelligence like Sherlock could. He didn’t even know why he was so obsessed with Sebastian. The teenager seemed like your run of the mill rebel. Nothing more. But Jim couldn’t stop the nagging feeling that he was hiding something.  
*  
Jim had taken to spending his lunch time in the alley behind the school. He only ever saw a few students there, exchanging money for drugs or sexual favors. They never bothered him, because he looked like he was either high or homeless when he sat against the wall with his hood disguising his face.

He was sat against the cold brick wall once again that Thursday. His ‘urges’ had gotten bad, he hadn’t done something destructive in over a week. That used to be fine. But pain, his or another’s, was like a drug to him. It started affecting him less and less, he needed it more. He couldn’t stand to be around those idiots for much longer. He’d end up slitting someone’s throat sooner or later. 

He took his knife from his pocket, he had to keep it close nowadays. He flicked it open and stared at the potentially deadly blade. It was beautiful, a word he didn’t use often. Beautiful was reserved for things like blood, bruises, and the desperate sounds animals made as light left their eyes.

What would it be like to take a human life? Would they plead for mercy? Would they cry out in pain as the light left their eyes too? Jim laughed, what noise would he make when he died? Would Jim plead? Did Jim have any light in his eyes that could go out?

A low whine brought him out of his thoughts. Jim looked up to see a skeletal, matted stray dog limp towards him slowly, its head lowered in defeat. One of its eyes had been gouged out and in its place was a festering, infected wound. It yelped again as he watched it, perhaps asking for food or attention.

Jim gripped the knife so tightly his knuckles turned white. He could barely control himself, the only thing stopping him from gutting the mutt was the fact that he was in a semi-public area. Anyone could walk back here and see Jim covered in the dog’s hot, crimson blood.

He’d just have to handle them too, if that happened.  
*  
Sebastian sat in the cafeteria with his friends Greg, Sally, John, and Anderson. Others sat with them too, but Sebastian couldn’t be bothered to learn their names. He had some girl beside him chattering away about some movie she’d seen recently. He dully recalled that he’d slept with her last week at some party. He hoped she’d lose interest soon.

He wasn’t close to any of his friends, he only sat with them because he had nowhere else to sit. Well, he could technically sit anywhere, but he was expected to sit here because the rest of the popular kids did too. The only time he hung around any of these kids was at parties, otherwise he spent his time alone.

He pulled away from the mystery girl and stood up, “I’ll be right back.” He muttered, grabbing his bag and leaving. He walked around to the back of the school to have a smoke, he normally wouldn’t smoke at school but today had been tedious.

As Sebastian walked around the building he lit up, almost immediately feeling calmer. That’s when he saw the blood. Red stained the grey pavement of the alleyway, it stained the brick walls and it soaked into the trash littering the ground. It stained the mangled corpse of a dog, its intestines hanging from its belly and its throat cut so deeply that, if not for the creature’s spine, it might as well have been beheaded.

It stained skeletal hands that were so pale they could’ve been blue.

And it filled Sebastian with a feeling he’d never experienced before, better than a hundred fights or horror movies. For lack of a better word, the blood was beautiful. Sebastian let out a breath, louder than expected.

The image was shattered when the figure hunched over the corpse spun around and looked up at him. Sebastian recognized that face, he just couldn’t place it. The boy stared at him with dead eyes, expressionless. Then he stood, tucking the knife into his pocket and slinging his bag over his shoulder.  
As the boy passed Sebastian he leaned close to him, “Be a good boy and stay quiet about this, alright Sebby?”


	3. Joined at the Hip

**Summary for the Chapter:**

> Jim is lucky enough to get the opportunity to spend more time with Sebastian.

Sebastian couldn’t believe what had happened. The rest of the day had been a blur, he couldn’t stop thinking about what had happened. Who was that boy, why was he so familiar looking? Better yet, why hadn’t Sebastian told anyone what he’d seen? And why did all that blood make him so… excited?

Sebastian tried to shake these thoughts from his head as he drove home, his little sister Molly in the passenger seat, telling him about her science club. He wasn’t really listening but it was nice to know that she at least was having a normal high school experience. 

When they arrived home their mother had also just arrived. Sebastian and Molly’s father had walked out on them when Sebastian was six, and their mother had had to support them on her own until three years ago when they received the news that their father had died and left them several hundred thousand dollars. Their mother hadn’t had to work to support them anymore but she insisted that if she didn’t she do something she would go crazy. So she worked at a flower shop in town.

Sebastian greeted his mother and retreated to his bedroom to watch a movie and maybe settle his nerves. The terrible acting and over-the-top gore didn’t help though, it only made him think back to earlier, the sound of that boy’s voice, the coldness of his eyes. It was terrifying and exhilarating at the same time. The blood covering his hands, the blood covering his knife. It all made him feel something… it made him feel alive. 

*  
The next day in first period he heard people talking about the dog. It had been found by a cafeteria worker after school yesterday. Some people lamented the poor dog’s life, and others whispered about the possibility of it being a ritual sacrifice or a sign that a student would soon reach the same fate. But nobody knew who it had been. The school was too cheap for surveillance cameras to be installed back there and they reasoned that nobody really hung out by the dumpsters anyways. 

The buzz died down by the end of first period. By the time Sebastian made his way to third period chemistry he had almost succeeded in putting it out of his mind. The class started out fine until their teacher paired them up for a semester-long project. 

“I want you and your partner to write a ten page essay and develop an experiment to show how you can apply chemistry to the real world. I will be pairing you up myself so that you can focus on your project and only your project. Donovan and Lestrade will be paired together, Alexander and Browne, Garland and Finch, Moran and Moriarty…” The teacher droned on and Sebastian looked around for his partner but realized someone had just taken the seat beside him and opened their textbook. He turned to see a horribly familiar face staring back at him innocently.

The boy from the alley. Moriarty. His lab partner.

Moriarty raised an eyebrow at him, “Well? Try not to stare all day Sebastian. Didn’t your mother tell you it was rude?”

Sebastian continued to stare, “You… you’re-“

The other teenager cut him off, “James Moriarty. Yes, your partner in this dreadful project. Any idea what you’d like to do the project on?”

“Are you just going to ignore the fact that I saw you-“ 

Jim pressed a finger against Sebastian’s lips to silence him, “Hush now Sebby there are people present. I’ll talk to you later. Now, let’s figure out our project hmm?”

*

The rest of the day went just fine until the end of his sixth period class. Jim had stood up to leave the classroom when a pair of hands connected with his chest and sent him - and all of his books – to the grimy floor.

Jim looked up to see one of his classmates sneering down at him, Carl Powers, “Get out of my way freak. Nobody’s gonna help you, you don’t even have any friends!” He cackled obnoxiously and walked off. 

Jim pushed himself up and slowly gathered his belongings. Carl Powers. One of his most annoying abusers. Ever since kindergarten the bigger boy had taken out his frustrations on Jim, finding him to be any easy alternative to dealing with his own insecurities. 

Normally an event like this wouldn’t bother him, but Carl had interrupted a very… important meeting of his. Jim made his way to the boy’s bathroom, brushing the grime from his clothes as he went. 

The parking lot was crowded, students hurrying to escape the confines of the school they loathed so much. They darted between cars and in front of buses, self-preservation be damned. Normally Jim didn’t bother crossing through the busy lot, preferring to take the emergency exit on the other side of the school to avoid people altogether, but today he wasn’t walking home. Today he had a mission.

Through diligent ‘study’ (Jim refused to call it stalking) of Sebastian, Jim knew that Sebastian preferred to park his car in the farthest corner of the lot to lessen the chance of any sort of harm coming to his precious vehicle. He wasn’t disappointed and found the ridiculous muscle car in a secluded, trash littered area, its owner nowhere in sight.

*

Sebastian made his way towards his car, assuming he was going to find Molly waiting for him, irritable that he had taken so long. What he didn’t expect however, was to find his sister excitedly talking to one Jim Moriarty.


	4. Meet the Parent

**Summary for the Chapter:**

> Sebastian take Jim home with him.

**Notes for the Chapter:**

> So sorry it took so long to update!

“What are you doing here?”

Jim felt a hand grab onto his shoulder and suddenly found himself staring up at Sebastian Moran. A dramatic smile lit up Jim’s face, “There you are Sebastian! I was just talking to your lovely sister here.” He gestured towards Molly, who nodded enthusiastically.

“Jim is riding home with us so you guys can work on your chemistry project, isn’t that wonderful?”

Sebastian nearly choked, “Uh… y-yeah Molly, wonderful.” He offered a weak smile, “Just get in the car okay? I need to have a word with Jim here.” 

As soon as Molly was out of earshot Sebastian tugged Jim aside, grabbing the smaller boy’s shoulders and forcing him to look up at Sebastian, “What do you think you’re doing?” He hissed, scowling down at Jim.

Jim met Sebastian’s eyes and smirked, “I only want to work on our project… we are partners you know, and I expect us to get a good grade.”

“You think I’m just going to let you come home with me? After I saw what you were capable of?” Sebastian shook his head in bewilderment, “Why would I let you near my family?”  
A sultry smile overtook Jim’s face and he fixed Sebastian with big innocent eyes, “I think you want to take me home because you know what I’m capable of. I saw the look on your face Sebby, and I’ve heard the rumors, I know how much you hold yourself back in those fights. I excite you.” He leaned forward in Sebastian’s grip, “That’s rare for you isn’t it?”  
Sebastian shoved Jim away from him, lip curled in disgust, “Get in the car.”

*

Molly and Jim chatted excitedly the entire drive. Jim acted like a completely different person around her, and Sebastian would be lying if he said that didn’t set his teeth on edge. How dare someone like him, a wolf, hide behind a sheep’s mask? And how did Sebastian almost find himself buying Jim’s bullshit?

Sebastian pointedly ignored them for the duration of the ride, not speaking until they pulled up to their house.

“Alright,” Sebastian sighed, “Everyone out.”

Molly exited the car and went inside, leaving Jim alone with Sebastian once again. The younger teen leaned forward from his place in the back seat, staring up at the house, “So this is the Moran residency. I’ll admit, its every bit as cookie-cutter family-friendly suburban lifestyle as I imagined.”

“Let’s just go in alright?” Sebastian asked uncomfortably, getting out of the car and walking towards the front door, not checking if Jim followed him.

*

The moment he crossed the threshold Jim found it hard to keep following behind Sebastian. The house wasn’t huge, but it was unlike any house he’d ever been in (He’d never been to anyone’s house but his own though so there wasn’t much to compare it to). The entryway was lit by soft yellow lights and the walls were decorated by pictures of a smiling blonde child and a smaller brunette little girl throughout various ages. How domestic.

Jim rolled his eyes and followed Sebastian into the kitchen where his mother had started baking. The kitchen was similar to the rest of the house, lit by warm lights and decorated as if it was straight out of an interior design magazine. Sebastian and Molly’s mother was a small, kind looking woman who had probably been beautiful in her youth. Her long brunette hair had streaks of grey through it and faint crow’s feet surrounded her soft eyes. She looked up as they entered.

“How was school my dear? And who’ve you brought home with you?” She smiled warmly at Jim, which, if he was being honest, made him feel deeply uncomfortable.  
Sebastian shifted his weight awkwardly, “It was fine mum, and this is Jim, he’s my partner in Chemistry.”

Jim smiled charmingly and stuck out his hand in greeting, “James Moriarty ma’am, it’s a pleasure to meet you. You have such a lovely home.”

She shook Jim’s hand and smiled back at him, “Thank you James! It’s so wonderful to see that my ‘Bastian here can make friends who actually have manners. Will you be staying for dinner?”

“Oh, I wouldn’t want to be any trouble.” He replied with tasteful bashfulness.

She waved a hand in dismissal, “Of course not, we would love to have you stay. Well, I wouldn’t want to keep you two geniuses from your work, I’ll be here if you need anything.”  
Jim thanked her and left the room with a silent Sebastian, who looked hopelessly lost since the conversation beforehand. The pair made their way upstairs to the blonde’s bedroom without a word, but as soon as they entered and closed the door behind them Sebastian wheeled on Jim, “What was all that?”

Jim sat himself on Sebastian’s mattress and raised an eyebrow, looking at his nails with great interest, “Whatever do you mean darling?”

“You know what I mean! What was that show you put on for my mum? I’ve never seen you act like that.”

“Yes well the situation called for me to have… appeal. Charisma, you know? There’s no point in being likable at school, nobody there has earned my company.” Jim stretched out on Sebastian’s bed like a cat.

The other teen sat on the bed beside him grudgingly, “Why did you come home with me today? I know it wasn’t because of our project.”

“Look at you! Using your detective skills. Yes you’re right, my intentions were not as pure as receiving an A on our project. I wanted to talk to you.”

“About yesterday?” Sebastian asked hesitantly, looking down at the smaller boy.

Jim rolled onto his stomach to look up at Sebastian through his eyelashes, folding his hands beneath his chin, “Not exactly.”

**Author's Note:**

> Please feel free to leave constructive criticism and tell me if any of my references to the actual show and/or characters are incorrect. Thank you for reading.


End file.
